2,4-D对赤子爱胜蚓抗氧化系统和基因表达的影响

Effects of 2,4-D on the antioxidant system and the gene expression of the earthworm Eisenia fetida

2,4-二氯苯氧乙酸(2,4-D)是世界上最常用的除草剂之一.大规模的使用导致其进入土壤环境中,但其对土壤生物的毒性及其作用机制还不完全清楚.通过滤纸接触法研究了2,4-D对赤子爱胜蚓(Eisenia fetida)抗氧化系统和功能基因表达的影响.结果表明,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、谷胱甘肽S转移酶(GST)、总抗氧化能力(T-AOC)和谷胱甘肽(GSH)随暴露时间的延长或暴露剂量的增加呈现先升高后降低的趋势,而丙二醛(MDA)在暴露3 d和5 d时出现显著升高,说明2,4-D暴露损害了蚯蚓机体抗氧化系统,最终导致脂质过氧化的发生.热休克蛋白70(hsp 70)钙网蛋白(crt)基因发生了显著变化,表明hsp70和crt作为分子伴侣在保护细胞免受氧化损伤中可能起重要作用.Annetocin(ann)基因的显著下调,表明2,4-D暴露影响蚯蚓生殖,而翻译调节肿瘤蛋白(tctp)基因的抑制可能会影响蚯蚓细胞生长,使细胞更易于发生细胞凋亡.实验结果说明,2,4-D可进入蚯蚓并干扰其抗氧化系统和hsp70,crt,ann和tctp基因表达,造成机体氧化损伤并影响其生长和繁殖.

2,4-dichlorophenoxyacetic acid(2,4-D)is one of the most commonly used herbicides in the world.However,the toxicity of 2,4-D to soil organisms and its mechanism of action are still not fully understood when it releases into soil environment due to its large-scale application.The effects of 2,4-D on the antioxidant system and the functional gene expression of Eisenia fetida were studied in the present study through filter paper contact method.The results showed that the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),glutathione S-transferase(GST),and the contents of total antioxidant capacity(T-AOC)and glutathione(GSH)increased firstly and then decreased with the prolongation of exposure time or the increase of exposure dose,while malondialdehyde(MDA)increased significantly at 3 d and 5 d of exposure.These results indicate that 2,4-D exposure damages the antioxidant system of earthworm and eventually leads to lipid peroxidation.The expressions of heat shock protein 70(hsp 70)and calreticulin(crt)gene are also significantly changed,suggesting that hsp70 and crt may play an important role in protecting cells from oxidative damage.Significant downregulation of annetocin(ann)gene suggests that 2,4-D exposure affects reproduction,while inhibition of translation-regulated tumor protein(tctp)gene may affect the cell growth of earthworm and make cells more prone to apoptosis.These results suggest that 2,4-D could enter into earthworm and disturb the balance of the antioxidant system and the expression of hsp70,crt,ann and tctp genes,causing oxidative damage and affecting the growth and reproduction of earthworm.